Realization of two-dimensional (2D) systems of massless Dirac
fermions is of great fundamental importance, in the light of many
exotic phenomena obtained in such systems, such as zero modes,
fractional statistics, unconventional
Landau levels, parity anomaly, chirality, and anomalous quantum Hall
effects [1]}, [2]}, [3]}. However, two-dimensional
massless Dirac field have not been observed untill the creation of
graphene, a monolayer of graphite [4]}, [5]}.
Electrons in graphene, obeying a linear dispersion relation, behave
like massless Dirac fermions
[4]}, [5]}, [8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}.
